RAC的异步订阅+发送

异步订阅+发送：

// 异步订阅+发送
RACSignal *signal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
    NSLog(@"111");
    RACDisposable *disposable = [[RACScheduler scheduler] schedule:^{
        [subscriber sendNext:@1];
        [subscriber sendCompleted];
    }];
    return disposable;
}];
[[RACScheduler scheduler] schedule:^{
    NSLog(@"222");
    [signal subscribeNext:^(id x) {
        NSLog(@"333");
    }];
}];

NSLog(@"444");

2021-04-17 09:51:15.910231+0800 NetSchool[4306:1299513] 222

2021-04-17 09:51:15.911291+0800 NetSchool[4306:1299513] 111

2021-04-17 09:51:15.911447+0800 NetSchool[4306:1299513] 444

2021-04-17 09:51:15.911481+0800 NetSchool[4306:1299610] 333